Oh Brad,
What a great topic!
With me it was more a case of what wasn't I afraid of. I remember when I was about 3 my dad got me a wind up hillbilly. He only wound it up once. It scared my feet out of my socks and I cried for ages.
At around the same age we went on holiday to a Scottish island called Gigha (or something like that) and in our cottage, upstairs, behind a weird little curtain, was a pipe. That's right: I was scared of a piece of plumbing. I think it was the curtain that did it - somehow it was like it was hiding. Whenever my parents want to remind me I'm a weirdo they bring this up.
When I was a bit older I found out about vampires. These were the bane of my life until my teens. When I was about eight it seemed as though every nightmare was about my friends and family being "turned". I also developed an unhealthy idea that one of my parents siamese cats was a vampire, and so I was always rather careful around him. Also I used to mentally draw lines out from my parents copy of Dracula on the shelf (vertically, horizontally and in-and-outally) and when I was going around the house by myself I used to duck, jump and sidestep so that I wouldn't cross any of the lines, and presumably, wake the beast.
I was really afraid of the dark, because I had got a ghost book when I was about eight, which had this very specific photo (probably quite famous in ghost hunting circles, and probably also a fake I realise now) of a hideous looking monk ghost in a church. I was always afraid I was going to meet him in the dark.
Also when I was a kid my room seemed to creak and ping so much that I was convinced there was something malevolent creeping around to get me. I used to picture this thing with a face the size of a dinner plate and a huge sausage smile. Eww. I don't think it ever did though, thankfully.
Also deep water, though that's something I've only started noticing in the last ten years.
Ah, that's better. Thanks for letting me get it off my chest.